Such devices are well known. We can see an example of them in U.S. Pat. No. 2,222,036. The regrooving knife has the general shape of a "U", with the exact profile of the groove one wishes to cut, or deepen. This knife is usually heated to facilitate the operation. It is very important to respect a certain regrooving depth. To achieve, this, the portable devices for manual use have a base that is supported by the surface of the tire to be regrooved, the depth of knife penetration being adjusted in relation to this base.
Absolute control of this regrooving depth is important in order to not reach the reinforcement contained in the carcass, the tire belt or the belt protection ply. This is the reason why attempts have been made to automate this regrooving operation, in order to guarantee its quality and consistency. The U.S. Pat. No. 4,147,196 describes a machine with a probe that measures either the position of the metallic plies laid under the tread, or the exact relative position of the tire surface, in order to control the depth of penetration of the regrooving knife.
The purpose of the present invention is to make this regrooving operation even more precise. This regrooving operation is particularly used in heavy-duty truck tires. Regrooving obviously prolongs the tire's use. When a regrooved tread pattern wears out, the tire is usually recapped, resulting in a new use cycle that could end with a second regrooving. Therefore, it is extremely important that the regrooving operation not destroy the reinforcement structure of the tire, not only for safe operation of the regrooved tire, but also for economic reasons. Any degradation of the reinforcement structure risks making the carcass unusable for recapping or, at the very least, making recapping more costly.